1. Field of the Invention
The present invention relates to control apparatus for internal combustion engine.
Priority is claimed on Japanese Patent Application No. 2006-143787, filed May 24, 2006, the entire contents of which are incorporated herein by reference.
2. Description of the Related Art
In the past, to enhance the startability of internal combustion engines when the battery capacity decreased at very low temperatures or when the battery deteriorated, for instance, the use of a control apparatus that varied the torque characteristics of motor at specific voltages by switching the magnetic flux quantity by multiple circuits according to the number of turns of motor winding and according to the battery output voltage, is well known (for example, refer to Japanese Unexamined Patent Application, First Publication No. 2005-20795).
The control apparatus as an example of the related art mentioned above requires a plurality of circuits to be provided for changing motor torque characteristics to start the internal combustion engine. With the increasing complexity in the configuration of the apparatus, the size of the apparatus increases, and this becomes an issue.
Moreover, in a state where the battery temperature is low or when the state of charge has reduced, if current discharge is continuous, excessive voltage drop occurs, the power supplied to the motor reduces, and it is likely that the required torque necessary for starting an internal combustion engine may not be output easily. Furthermore, the issue of battery deterioration promoted by excessive voltage drop of the battery also arises.